Track if all stages modulate inputColor in computeInvariantOutput

include/gpu/GrProcessor.h

Index: include/gpu/GrProcessor.h
diff --git a/include/gpu/GrProcessor.h b/include/gpu/GrProcessor.h
index 5350015d67567dde0f9c29bd5416b0ea514801f1..bbcc919caa525ec545e1b4337a4030df5848bcf9 100644
--- a/include/gpu/GrProcessor.h
+++ b/include/gpu/GrProcessor.h
@@ -38,7 +38,8 @@ public:
     virtual ~GrProcessor();
 
     struct InvariantOutput{
-        InvariantOutput() : fColor(0), fValidFlags(0), fIsSingleComponent(false) {}
+        InvariantOutput() : fColor(0), fValidFlags(0), fIsSingleComponent(false),
+                            fInputIsOnlyModulated(true) {}

[bsalomon, 2014/10/13 19:52:49]

I seems like we should use multiply rather than modulated since all the
functions are mulByFoo. fStagesAllMultiplicative? fNonMulStageFound? 

[egdaniel, 2014/10/13 20:26:47]

Done.

 
         void mulByUnknownOpaqueColor() {
             if (this->isOpaque()) {
@@ -53,15 +54,15 @@ public:
 
         void mulByUnknownColor() {
             if (this->hasZeroAlpha()) {
-                this->setToTransparentBlack();
+                this->setToTransparentBlackPriv();
             } else {
-                this->setToUnknown();
+                this->setToUnknownPriv();
             }
         }
 
         void mulByUnknownAlpha() {
             if (this->hasZeroAlpha()) {
-                this->setToTransparentBlack();
+                this->setToTransparentBlackPriv();
             } else {
                 // We don't need to change fIsSingleComponent in this case
                 fValidFlags = 0;
@@ -74,20 +75,20 @@ public:
         }
 
         void setToTransparentBlack() {
-            fValidFlags = kRGBA_GrColorComponentFlags;
-            fColor = 0;
-            fIsSingleComponent = true;
+            this->setToTransparentBlackPriv();
+            fInputIsOnlyModulated = false;
         }
 
         void setToOther(uint8_t validFlags, GrColor color) {
             fValidFlags = validFlags;
             fColor = color;
             fIsSingleComponent = false;
+            fInputIsOnlyModulated = false;
         }
 
         void setToUnknown() {
-            fValidFlags = 0;
-            fIsSingleComponent = false;
+            this->setToUnknownPriv();
+            fInputIsOnlyModulated = false;
         }
 
         bool isOpaque() const {
@@ -108,6 +109,17 @@ public:
         SkDEBUGCODE(void validate() const;)
 
     private:
+        void setToTransparentBlackPriv() {
+            fValidFlags = kRGBA_GrColorComponentFlags;
+            fColor = 0;
+            fIsSingleComponent = true;
+        }
+
+        void setToUnknownPriv() {

[bsalomon, 2014/10/13 19:52:49]

usually term such things internalSetToUnknown().

[egdaniel, 2014/10/13 20:26:47]

Done.

+            fValidFlags = 0;
+            fIsSingleComponent = false;
+        }
+
         bool hasZeroAlpha() const {
             return ((fValidFlags & kA_GrColorComponentFlag) && 0 == GrColorUnpackA(fColor));
         }
@@ -128,6 +140,7 @@ public:
         GrColor fColor;
         uint32_t fValidFlags;
         bool fIsSingleComponent;
+        bool fInputIsOnlyModulated;
     };
 
     /**